1. Field of the Invention
This invention relates to wear resistant, heat resistant and corrosion resistant rings for use on spinning machinery, including ring spinning machines and twisting machines, which are used at a high speed.
2. Description of the Prior Art
Conventionally, rings for spinning machinery are made of carbon steel and subjected to a heat treatment by carburizing and quenching to attain a surface hardness of 800-900 Hv and a hardened depth of 0.4-0.5 mm. However, the useful life of rings for spinning machinery subjected to only the above heat-treatment has been 3-4 years in the cotton spinning field and 1-2 years in the man-made fiber spinning field, at the longest. The shorter service life of such rings made of carbon steel may be attributed to the fact that the ring temperature becomes high and the surface hardness becomes lower due to frictional heat which is generated when a traveller slides on a ring flange, with the result that sliding abrasion due to operations of the traveller increases. Also, conventional rings corrode easily, with the result of earlier exfoliation and abrasion and frequent yarn breakage in the spinning process.
With the object of eliminating the above demerits, some of the conventional rings for spinning machinery are made of alloy steel containing Al, Cr, etc. and are subjected to a hardening treatment, so as to improve hardness of the traveller moving over the surface of the ring and abrasion resistance. However, rings of spinning machinery of this kind have bad affinity to the traveller and therefore travellers do not run smoothly and running-in of travellers for many hours is required to obtain the stabilized spinning condition. Also, due to low toughness of the hardened layer, useful life of the rings is comparatively short.
Since conventional rings for spinning made of carbon steel or alloy steel show high abrasion resistance during sliding of the traveller, these rings involve increased spinning tension and frequent yarn breakage in the spinning process. Therefore, conventional rings are not suitable for high speed operation and a spindle speed of around 16,000 r.p.m. is the maximum for them.
An object of the present invention is to provide rings for spinning machinery which solve the above problems, namely, rings having high surface hardness, a smooth surface, improved abrasion resistance, improved heat resistance and improved corrosion resistance suitable for the high speed spinning operation, high productivity, a longer service life and spinnability of high quality yarn.